Sound record



Patented Sept. 28, 1937 UNITED STATES PATENT OFFICE No Drawing.

Original application October 5,

1929, Serial No. 397,758. Divided and this application February 19, 1932, Serial No. 594,148. In Canada September 18, 1930 2 Claims.

This application is a division of my applica tion, Serial No. 397,758, filed October 5, 1929.

This invention relates to records for recording or reproducing sound and relates more particu- 5 larly to such reproducing records as are employed with sound amplifying devices.

An object of my invention is to prepare sound records from which tones of purer quality than has heretofore been possible may be produced.

Further objects of my invention will appear from the following detailed description.

Sound reproducing records have heretofore been made of materials containing resins such as shellac and hard filling materials such as silicon,

iron oxide and the like. Such records are open to the objection that they emit harsh tones due to the presence of these materials. When sound reproduced from such records is amplified, the harshness and scratchy sounds are accentuated and the result is altogether displeasing to the ear.

I have found that if sound records are made of athermoplastic composition containing organic derivatives of cellulose and a suitable plastifier or softening agent, which composition does not 2 contain the hard filling material heretofore employed in sound records, the sound reproduced from such records is clear and free of distortions and scratchy noises, and is substantially exactly the same as the original sound that is intended to be reproduced.

In accordance with my invention I prepare sound records, the reproducing surface of which is composed of a thermoplastic composition containing an organic derivative of cellulose and a suitable plastifier in suitable proportions and which is free of hard filling material.

The organic derivative of cellulose employed in making the thermoplastic material may be of lose acetate, cellulose formate, cellulose propionate and cellulose butyrate while examples of cellulose ethers are ethyl cellulose, methyl cellulose and benzyl cellulose. As to the plastifier or softening agent, any suitable one may be employed, examples of which are xylene monomethyl sulfonamid, triacetin, triphenyl phosphate, dlbutyl tartrate, diethyl tartrate, diethyl phthalate, etc. As to the proportions of plastifier employed, generally I have found that amounts varying from 35 to 60%, preferably 40%, of the weight of the organic derivative of cellulose present produce excellent results.

As stated the thermoplastic composition should be free of hard filling materials. While I prefer Examples of organic esters of cellulose are celluto employ no filling materials at all, if it is desired to reduce the cost of the product, a soft or lubricating filler such as talc, not to exceed 25% of the weight of the plastic material, may be employed. To impart color, a suitable dye 5 such as nigrosin may be added, but hard pigments are to be avoided.

The thermoplastic material may be made in any desired manner. I prefer to make a plastic mass by gelatinizing the organic derivative of cellulose 10 and a plastifier and any other permitted ingredient with a volatile solvent such as acetone, alcohol or benzene, working the mass on heated malaxating rolls to remove excess solvent, and then forming sheets from the mass. The sheets 15 so formed may be cut into discs corresponding to the size of the record desired, and these discs are then pressed between the sound matrices at elevated temperatures to form the finished record. 7 20 If desired the thermoplastic material may be made in the form of powder by finely dividing the plastic material formed by the gelatinization of the ingredients by a solvent and removing the sol vent, or such powder may be formed by finely 25 grinding the dry derivative of cellulose and the plastlfier, with or without other permitted ingredients. These powders may be molded under heat and pressure between the sound matrices to produce the sound record.

If desired the whole sound record need not be made wholly of the thermoplastic composition, but the interiors may be made of cheaper material such as plastics, laminated paper or fabric and the like, which may be inserted as cores with- 35 in the plastic composition.

Sound records produced in accordance with the invention reproduce clear sounds free of distortions and extraneous noises. While-the volume of sound reproduced from such records by the ordinary mechanical graphophone is not as loud as those produced from records made in accordance with the prior art, such sound may be readily amplified by electrical or other desired means to any desired extent and such amplified sound is pleasing to the ear.

Because of the excellent quality of the sound reproduced therefrom, records made in accordance with this invention are eminently suited for reproducing sound that is to be greatly amplified as in public halls and theatres, and are therefore of great utility in this connection. An important application of this invention is in connection with making sound records to be used in sound reproducing apparatus synchronously combined with cinematographic apparatus to produce socalled sound motion pictures. In order further to illustrate this invention but without being limited thereto, the following specific example is given. 1

Example A plastic composition is made by mixing the following ingredients:

. Parts by weight Cellulose acetate 100 Xylene monomethyl sulfonamid 17.2 Triphenyl phosphate 11.4 Triacetin 11.4 Benzol for the ethyl alcohol denatured with methyl alcohol 40 The ingredients are thoroughly mixed at elevated temperatures whereupon a gelatinous mass is produced, and then this gelatinous mass is worked on heated malaxating rolls to drive out the volatile solvents which are the benzol and the denatured alcohol. The mass may be worked on the rolls until hard slabs are formed and these slabs are then seasoned. The seasoned slabs are then cut into discs which may be molded between sound matrices to form the finished record.

As a variation the plastic mass is worked on heated rolls to form sheets, these sheets are then sition which is free from hard material and contains an organic derivative of cellulose and a plasticizer in an amount of from 35 to 60% of the organic derivative of cellulose present.

2. A sound record having a reproducing surface made of a non-resinous thermoplastic composition which is free from hard material and contains cellulose acetate and a plasticizer, comprising a mixture of xylene monomethyl sulfonamid, triphenyl phosphate and triacetin, in an amount of substantially 40% of the weight of the cellulose acetate present.

CAMILLE DREYFUS. 

